U.S. patent number 5,782,823 [Application Number 08/628,456] was granted by the patent office on 1998-07-21 for laser device for transmyocardial revascularization procedures including means for enabling a formation of a pilot hole in the epicardium.
This patent grant is currently assigned to Eclipse Surgical Technologies, Inc.. Invention is credited to Richard L. Mueller.
United States Patent |
5,782,823 |
Mueller |
July 21, 1998 |
Laser device for transmyocardial revascularization procedures
including means for enabling a formation of a pilot hole in the
epicardium
Abstract
An apparatus for performing a laser myocardial revascularization
of a human heart comprises a hand-held device with an elongated
flexible lasing assembly including an axially movable fiber bundle
which can be placed into the chest cavity of a patient. At the
distal head end of the device laser energy from the distal end of
the fiber bundle is initially reduced to form a relatively small
opening in the epicardium of the heart. The fiber bundle is moved
through the opening so that lasing with full laser power takes
place beneath the epicardium to form a larger channel through the
myocardium that extends into the left ventricular cavity. After the
channel has been formed, the optical fiber bundle is retracted from
the channel and back through the small epicardium opening so as to
minimize operative bleeding and allow sealing of the epicardium
after the apparatus is removed.
Inventors: |
Mueller; Richard L. (Byron,
CA) |
Assignee: |
Eclipse Surgical Technologies,
Inc. (Sunnyvale, CA)
|
Family
ID: |
24518955 |
Appl.
No.: |
08/628,456 |
Filed: |
April 5, 1996 |
Current U.S.
Class: |
606/7; 606/11;
606/15 |
Current CPC
Class: |
A61B
18/22 (20130101); A61B 2017/00247 (20130101); A61B
2018/00392 (20130101); A61B 2017/306 (20130101); A61B
2018/00291 (20130101); A61B 2017/0243 (20130101) |
Current International
Class: |
A61B
18/20 (20060101); A61B 18/22 (20060101); A61B
17/30 (20060101); A61F 9/007 (20060101); A61F
9/008 (20060101); A61B 17/00 (20060101); A61B
17/02 (20060101); A61B 017/36 () |
Field of
Search: |
;606/7,10,11,13-16
;607/89 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0515867 A2 |
|
Feb 1992 |
|
EP |
|
WO 94/14383 A1 |
|
Jul 1994 |
|
WO |
|
Primary Examiner: Smith; Ruth S.
Attorney, Agent or Firm: Erickson; Roger W. Castaneda; Janet
Kaiser Sears; Christopher N.
Claims
What is claimed is:
1. A transmyocardial revascularization (TMR) hand-held device for
performing TMR on a patient's heart, the device comprising:
a handle portion;
a tubular neck portion connected to the handle portion;
a head portion on a distal end of the tubular neck portion, the
head portion forming a distal end contact surface;
an optical fiber having a proximal end configured for connecting to
a laser energy source, the optical fiber extends through the handle
portion, the neck portion and the head portion;
an adjustment means disposed on the handle portion for moving the
optical fiber within the handle and neck portions and head portion;
and
irradiation control means for providing reduced laser pulse energy
from the optical fiber's distal end at a first position proximate
to the epicardium thereby enabling formation of a pilot hole in the
epicardium,
wherein the optical fiber can thereafter be moved axially from the
first position by the adjustment means and allow nonreduced laser
energy to emanate from the optical fiber's distal end whereby
enabling formation of a myocardial revascularization channel.
2. The device of claim 1 wherein the irradiation control means is a
means for partially shielding the optical fiber's distal end
whereby laser beam energy therefrom is reduced.
3. The device of claim 1 wherein the head portion has a concave end
face.
4. The device of claim 3 wherein the head portion includes at least
one opening on the distal end contact surface, the at least one
opening communicates through a tubular member extending through the
handle portion, the tubular member is configured for connecting to
a vacuum source,
whereby activation of the vacuum source: a) draws the epicardium
against the distal end contact surface, b) assists in ablated
tissue removal and c) draws blood into the revascularizing
channel.
5. The device of claim 1 wherein the adjustment means includes
within the handle portion an axial lumen, a movable shuttle within
the axial lumen that is connected to the optical fiber, the optical
fiber extends axially within the lumen, and a control knob attaches
to the shuttle and extends outwardly from the handle portion,
whereby the optical fiber can axially move within the handle
portion by moving the control knob.
6. The device of claim 1 including at a central opening of the head
member a sensing means for predetermined positioning of the optical
fiber's distal end relative to the epicardium.
7. The device of claim 6 wherein the sensing means responds to
increased axial force from the optical fiber thereby allowing the
optical fiber to pass through the central opening and egress into
myocardial tissue.
8. The device of claim 6 wherein the sensing means includes an
expandable split ring that seats within a groove in the central
opening.
9. The device of claim 8 wherein the split ring has an inner
diameter that is less than the diameter of the optical fiber
whereby when the optical fiber's distal end urges against the split
ring and emits laser energy, the slit ring partially shields laser
irradiation from the optical fiber thereby forming a pilot hole in
the epicardium.
10. The device of claim 9 wherein the split ring has a metal alloy
coating that absorbs laser energy.
11. The device of claim 1 wherein the head portion forming the
distal end contact surface includes at least one circular ridge
member for positional stability.
12. The device of claim 1 wherein the head portion includes a means
for attaching to the tubular neck portion.
13. The device of claim 1 further including rotational adjusting
means for radially orienting the neck portion relative to the
handle portion.
14. The device of claim 13 wherein the rotational adjusting means
is a jam nut disposed on the neck portion which threadedly attaches
to the handle portion.
15. The device of claim 1 wherein the tubular neck portion has an
offset curved shape at the neck portion's distal end and is made of
a malleable material thereby allowing changes of the head portion's
orientation relative to the handle portion.
16. A method for myocardial revascularization of a patient's heart
comprising the steps of:
a) providing access to the patient's heart and positioning an
optical fiber whose proximal end connects to a laser source and
whose distal end is for laser pulse emissions, the optical fiber's
distal end initially is juxtaposed to an irradiation control means
for providing reduced laser pulse emissions from the optical fiber
at an initial position;
b) placing the optical fiber's distal end near the heart's surface
at the initial position;
c) pulsing the laser source at the initial position forming a pilot
hole in the epicardium;
d) advancing the optical fiber past the irradiation control means
through the pilot hole; and
e) pulsing the laser source while advancing the optical fiber's
distal end into the heart's myocardium thereby allowing non-reduced
laser energy to emanate from the optical fiber's distal end and
forming a revascularizing channel.
17. The method of claim 16 wherein in step a) of providing a
revascularizing device with the optical fiber, the device further
includes a head portion on a distal end of a tubular neck portion,
the head portion has an opening on the distal end's contact surface
communicating through a tube to a vacuum source; and
prior to the step c), applying suction to the distal end's contact
surface thereby causing the epicardium to be drawn firmly against
the distal end's contact surface.
18. The method of claim 16 further including the step of applying
suction to the distal end's contact surface as the optical fiber is
moving during channel formation in step e).
19. The method of claim 16 further including the steps of
withdrawing the optical fiber and continuing to apply suction to
the distal end's contact surface thereby drawing blood into the
revascularizing channel, thus increasing myocardial
revascularization and removing ablated tissue.
Description
FIELD OF THE INVENTION
This invention relates to the field of laser surgery, and more
particularly to an improved laser surgery device for use in
procedures for increasing the flow of blood to heart muscle.
BACKGROUND OF THE INVENTION
Medical science has developed a wide variety of methods for
counteracting the effects of cardiovascular disease including open
heart and by-pass surgery. Non-surgical procedures such as
percutaneous transliminal coronary angioplasty, laser angioplasty,
and atherectomy have also been developed.
One alternative to the aforementioned procedures is known as
Transmyocardial Revascularization (TMR). In such procedures,
channels are formed in the ventricle wall of the heart with a
laser. These channels provide blood flow to ischemic heart muscle.
A history and description of this method has been documented by Dr.
M. Mirhoseini and M. Cayton on "Lasers in Cardiothoracic Surgery"
in Lasers in General Surgery (Williams & Wilkins; 1989) pp.
216-233.
As described therein, a CO2 laser was used to produce channels in
the ventricle from the epicardium through the myocardium. This
procedure followed a surgical incision in the chest wall to expose
the heart. Laser energy was transmitted from the laser to the
epicardium by means of an articulated arm device of the type
commonly used for CO2 laser surgery. The beam was coherent and
traveled as a collimated beam of laser energy through the
epicardium, the myocardium and the endocardium into the left
ventricle cavity. The epicardium received the highest energy
density and therefore normally had the largest area of heart tissue
removed compared with the endocardium which was approximately 1 cm
deep to the epicardium. The resultant channel through the
myocardium was funnel-like. A problem associated with the above
procedure arose because laser perforation of the epicardium caused
bleeding from it outwardly from the left ventricle after the
procedure. External pressure by the surgeon's hand on the
epicardium of the heart was often needed to stop bleeding from the
ventricle to the outside through the hole produced by the laser in
the epicardium. However, this procedure was usually only partially
successful because it resulted in a significant amount of blood
loss and/or an excessive amount of time required to stop the
bleeding. Both factors could jeopardize the success of the
revascularization procedure.
In a proposed improvement in an TMR procedure described in Hardy
U.S. Pat. No. 4,658,817, a needle was added to the distal tip of an
articulated arm system, with a beam of laser energy being passed
through the lumen of the needle. The metal tip of the needle of the
device was used to pierce most of the myocardium and the laser beam
then was used to create the desired channel through the remaining
portion of the myocardium and through the adjacent endocardium. In
the Hardy procedure, the hollow needle used to deliver laser light
was subject to being clogged by tissue or blood which could flow
into the needle, thus blocking the laser light from impinging the
myocardium. Also, the metal rim of the needle could be damaged by
the intense laser light and leave contaminating metal remains
within the myocardium which are potentially hazardous.
Another proposed TMR procedure is described in the Aita, et al U.S.
Pat. No. 5,380,316. Aita, commenting on the Hardy needle device,
contends that mechanical piercing was undesirable because it
entailed some degree of tearing of the pierced tissue, and that
tearing often leads to fibrosis as the mechanical tear heals, a
factor that severely diminishes the effectiveness of the TMR
treatment. Aita, et al also contends that exposure to metal may
cause fibrosis where the needle passes through tissue. The Aita, et
al patent describes an elongated flexible lasing apparatus which is
guided to an area exterior to the patient's heart and irradiates
the exterior surface to form a channel through the epicardium,
myocardium and endocardium. Thus, in the Aita et al procedure, the
epicardium is irradiated at a high energy density and therefore
should have a large area of heart tissue removed. Consequently, the
Aita, et al procedure has the same problems and disadvantages as
the prior Mirhoseini TMR procedure with respect to the
aforementioned bleeding problem in the outer surface of the
epicardium.
In a copending application Ser. No. 08/607,782 which is assigned to
the assignee of the present application, an improved apparatus and
method for TMR procedures is disclosed. In this application the
epicardium membrane of the heart muscle is first penetrated
mechanically by a hollow piecing member and thereafter the distal
end of a laser transmitting fiber is moved forwardly through the
myocardium as it emits pulses of laser energy to form a channel.
When the fiber element is retracted and the piercing member is
removed the opening that was made mechanically in the epicardium
tends to close to prevent excessive bleeding from the channel
formed in the myocardium.
Under certain operating conditions, the characteristics of the
epicardium membrane may vary so the physician may elect to use an
alternate means on the hand-held device for penetrating the
epicardium membrane during a TMR procedure which minimizes bleeding
after the procedure has been completed. Thus, it is desirable that
the physician be able to pierce the epicardium in the most
efficient manner and thereby minimize the size of the opening
necessary to accommodate the advancing fiber element. The improved
TMR device of the present invention solves these problems.
It is therefore a general object of the present invention to
provide an improved apparatus for performing laser myocardial
revascularization that solves the problems of the aforementioned
prior devices and procedures.
A further object of the present invention is to provide a less
invasive and safer apparatus for performing laser myocardial
revascularization which does not diminish the effectiveness of the
TMR treatment and eliminates the problem of excessive bleeding from
the patient's epicardium following the channel forming
procedure.
It is a further object of the present invention to provide an
apparatus for performing laser myocardial revascularization which
utilizes a reduced laser pulse to form a preliminary perforation
opening in the epicardium membrane to enable the passage of an
optical fiber means for forming a widened channel in the myocardium
and such a way as to minimize bleeding from and promote sealing of
the epicardium opening.
Still another object of the present invention is to provide an
improved device for performing a TMR procedure wherein an initial
small opening is formed in the epicardium to facilitate formation
of a larger cone-shaped channel whose wider end is at the
endocardium to promote blood perfusion from the left ventricular
cavity and whose narrow end is closed beneath the epicardium to
avoid excessive epicardial bleeding after the procedure.
Yet another object of the invention is to provide a device for use
in a TMR procedure which uses a concave distal end member that
contacts the outer surface of the epicardium, and then applies air
suction during the procedure to draw the epicardium into the distal
end member and thereafter draw blood into the channel just formed,
thereby enhancing the effectiveness of the procedure.
SUMMARY OF THE INVENTION
The present invention comprises a method and apparatus for combined
mechanical/laser myocardial revascularization of a human heart that
fulfills the aforesaid objectives. A hand-held device which
includes an elongated flexible lasing apparatus including an
optical fiber bundle that can be is inserted into the chest cavity
of a patient. In one form, the device includes a detachable distal
head end assembly including a circular, disk having a central bore
through which the distal tip of the fiber bundle can pass. A
restrictive sensing and positioning means is provided in the bore
for momentarily stopping the distal end of the fiber bundle at an
optimum distance from the surface of the epicardium. This
positioning means provides a temporary peripheral shield which
reduces the amount of laser energy from the fiber bundle by
decreasing the diameter of the laser beam emitted from its distal
end. When at this preliminary position against the sensing means, a
laser pulse is initiated to emit the reduced laser beam to form an
opening in that portion of the epicardium which has been sucked
into the concavity of the distal head end by a controlled vacuum.
After the epicardium opening has been formed, the fiber bundle is
advanced axially through it by the surgeon using a control on the
hand-held device. At this point, the positioning means is
expandable to allow passage therethrough of the fiber bundle which
also passes through the opening in the epicardium. After passing
through the epicardium opening, laser energy is emitted from the
distal end of the optical fiber bundle as it is advanced by the
surgeon into the myocardium tissue beyond the preliminary
epicardium opening. Thus, the myocardium is ablated with the full
beam of pulsed laser energy from said optical fiber distal end to
form a channel as it moves into the left ventricular chamber. As
the fiber element moves through the myocardium, an air suction
conduit connected to the distal head end assembly provides a means
for cleaning debris from the channel being formed and also for
keeping the outer surface of the epicardium firmly against the stop
member of the tip assembly. Sealing of the epicardium occurs after
the fiber bundle is withdrawn, the vacuum is discontinued to
release the epicardium with the concave distal end member, and the
device is moved.. Because the preliminary opening substantially
closes at this point, a minimum of bleeding occurs after each TMR
procedure. With the present device, the laser energy disbursed
through the myocardium as a noncollimated, expanding beam creates a
wider channel at the exit of the channel into the left ventricular
cavity than within the myocardium so that revascularization can
take place within the channel in the most effective manner.
Other objects, advantages and features of the present invention
will be apparent to those skilled in the art from the following
detailed description and the accompanying drawings.
DETAILED DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic view in section of a human heart showing
revascularization of the myocardium utilizing a device according to
the present invention.
FIG. 2 is an enlarged view in perspective showing a device
embodying principles of the invention for implementing the
revascularization procedure of FIG. 1.
FIG. 3 is an enlarged exploded and fragmentary view in section of
the device shown in FIG. 2 showing details of the handle portion
and the advancing mechanism for linear movement of the movable
fiber element.
FIG. 3A is a fragmentary view in section of the distal end member
for the device shown in FIG. 3.
Fig. 3B is a sectional view of FIG. 3A with the optical fiber in a
retracted position prior to advancement through the stop ring.
FIG. 3C is a sectional view of FIG. 3A with the optical fiber
advanced past the stop ring.
FIG. 4 is an end view of the distal end member of the device of
FIG. 3A.
FIGS. 4-9 are enlarged views in elevation and in section showing
the end member of FIG. 3A assembled and in operation during a
typical TMR procedure according to the invention.
DETAILED DESCRIPTION OF EMBODIMENT
With reference to the drawings, FIG. 1 diagrammatically depicts a
human heart 10 with the epicardium 12 of the left ventricle 14
exposed where a Trans-Myocardial Revascularization (TMR) procedure
according to the invention is to be performed. Preliminary to the
procedure the surgeon makes an incision in the patient's chest to
expose the outer wall of the heart's left ventricle. In a human
heart the wall of the left ventricle, is comprised of an outer
layer, the epicardium, the main muscle thickness or myocardium, and
the inner layer or endocardium. The epicardium is comprised of a
smooth, moist serous membrane which is somewhat tougher than the
other tissue layers of the heart muscle.
In carrying out the method of the present invention, the surgeon
utilizes a hand-held device 16 which is manipulated and operated to
form a series of revascularization channels 18 in the myocardium of
the patient's heart at selected spaced apart locations.
In accordance with the principles of the invention, each of the
channels is formed by first penetrating the epicardium membrane
with a restricted or reduced laser pulse to form a relatively small
opening through which the distal end of an optical fiber bundle 26
can thereafter be forced to engage the myocardium. The fiber bundle
is connected to a laser energy source 28 at its proximal end. Once
through this epicardium opening, full beam laser energy is emitted
in pulses from the distal end of the fiber bundle 26 as it is moved
forwardly to form the channel 18 in the myocardium and completely
through the endocardium. After the channel has been formed, the
distal end of the fiber bundle is retracted to a position within
the end member of the device 16 which can then be moved to another
location to repeat the procedure. In a typical TMR procedure a
number of channels, e.g. 30-50 may be formed depending on the
patient's condition. When the end member of the device is removed,
the relatively small opening in the epicardium substantially closes
due to the tissue resiliency, thereby minimizing any blood flow
from the channel just formed.
As shown in FIG. 2, the device 16 comprises a housing 20 adapted to
be hand held by the surgeon during an operative procedure, a
J-shaped neck member 22 attached to the housing and an
interchangeable distal head member 24 having a disk like shape with
concave surface 25 for contacting the outer surface of the
epicardium membrane. An optical fiber bundle 26 whose proximal end
is connected to the laser source 28 extends through the housing and
through the neck member to the distal end member 24. Within the
housing 20 the fiber bundle 26 is connected to a movable shuttle 30
(FIG. 3) which extends outside the housing and is connected to a
thumb actuated control member 32. Thus, movement of the control
member 32 by the surgeon will move the distal end 34 of the fiber
bundle beyond the concave surface 25 of the distal head member 24.
The vacuum line 36 extending from the vacuum source 37, such as a
conventional hospital vacuum type canister device, is connected to
a barbed inlet 38 in the housing 20. This inlet communicates with
an air passage 39 around the fiber bundle that extends the to
distal head member 24. Thus, when in use, a suction is provided at
the distal head member 24 of the device 16 which performs two vital
functions. First of all, the suction force draws the epicardium
tissue firmly against the concave contacting face 25 of the distal
head member 24 so that a relatively small opening 31 can be made in
the epicardium muscle fibers to allow the distal end of the fiber
bundle 26 to penetrate and engage the myocardium. As the fiber
bundle is advanced by the surgeon beyond the epicardium opening and
into the myocardium, laser pulses are produced from its distal end
34 to form a channel 18 through the myocardium. As the fiber bundle
continues to advance, the air suction provided helps to remove
debris caused by the laser and also to draw blood into the channel
to assure that the revascularization process will commence
properly. When the fiber bundle is retracted after forming a
channel, the distal end member 24 is moved away and the opening in
the relatively small epicardium closes naturally with a minimum of
bleeding.
Describing now the device 16 in greater detail, with reference to
FIG. 3. The housing 20, which may be molded from a suitable plastic
material, has an enlarged central cavity 40 to accommodate the
shuttle 30. The latter has a cylindrical portion which surrounds
and is firmly attached to the fiber bundle 26. Attached to the
cylindrical portion is a web portion 42 which extends through an
axial slot 44 in the housing. The web portion is connected to the
control member 32 on the outside of the housing 20 which preferably
has an arcuate configuration in cross section with a pair of
external, transverse ridge portions 46 that facilitate easy thumb
control by the surgeon.
Below the central cavity 40 is the barbed inlet 38 for the vacuum
line 36 which communicates with the air passage 39 to the distal
end member 24. An internal rubber disk 48 is provided within the
housing to seal the air passage from the central cavity 40. The
disk surrounds the fiber bundle and is held in place along its
periphery by an annular groove 49.
At its forward end, the housing tapers to a threaded end portion 50
having a tapered end surface 52 for receiving a flared end 54 of
the neck member 22. With the inner surface of this flared end in
contact with the tapered end surface 52, a jam nut 56 around the
neck member can be tightened on the threaded end portion 50 to
secure the neck member to the housing 20.
The proximal end of the optical fiber bundle 26 is connected to the
source or generator 28 of laser energy which is preferably a
Holmium laser that operates at a wave length in the range of 1.8 to
2.2 microns and a pulse frequency in the range of 2-25 Hertz. This
type of laser is preferable because it provides high absorption
efficiency, hemostosis and a moderate absorption range in
myocardium tissue, and is compatible with optical fiber delivery. A
conventional foot switch (not shown) can be used by the surgeon to
control the laser energy during a procedure.
At the laser generator, laser energy is supplied to the optical
fiber bundle 26 which, at its distal end, has a diameter of around
1.5 mm. The optical fiber bundle is comprised of a plurality (e.g.
37) of glass fibers 32 each having a diameter of 100 microns. These
glass fibers are held together by a suitable plastic material, such
a 353 ND Epoxy, and near its distal tip, the bundle is preferably
surrounded by an annular tantalum marker which serves to retain the
bundle in a closely packed geometric boundary surrounding the
bundled fibers is a plastic protective sheath such as polypropelene
having a wall thickness of 0.004 inches. Other fiber bundle
configurations could be used within the scope of the invention.
In the embodiment shown, the neck member 22 of the device 16 is a
tubular member having a uniform outside diameter (e.g. 0.120
inches) and inside diameter (e.g. 0.094 inches) preferably bent
into an angular "J" shape within which the optical fiber bundle 26
is slidable. This neck portion is preferably made from a stainless
steel which may be heat treated to make it malleable and thus
somewhat flexible. This enables the neck portion to be easily bent
so that its distal end head member 24 can be positioned to
accommodate the specific requirements of the surgical procedure
being performed.
Removably attached to the distal end of the tubular neck is the
enlarged disk-like head member 24 for the device 16. In the
embodiment shown in FIGS. 3A to 3C, the head member 24 has an
annular flange portion 27 with its previously described generally
concave surface 25 that surrounds a central opening 28 therein.
Preferably, this head member 24 is made of a molded plastic
material such as nylon, which allows the flange portion 27 to be
slightly flexible. One or more concentric circular ridges 29 with
sharp outer edges are provided in the end surface 25 so that the
head member 24 will retain its position when pressed firmly against
the epicardium of a beating heart.
In accordance with this invention, the initial opening 31 in the
epicardium is made by a laser beam of somewhat reduced diameter
before the fiber bundle 26 is caused to proceed forwardly through
the myocardium. Here, the circular distal head member 24 with its
concave inner surface is moved toward against the outer surface of
the epicardium, as shown in FIG. 4. At the center of the concave
surface 25 the opening 28 communicates with an axial bore 60 which
is smooth along its inner end and has internal threads at an
extended neck portion 62. These internal threads enable the distal
tip member 24 to be easily attached to and removed from the
threaded end of the neck portion 22 of the device 16. Just inside
the smooth bore 60 is a circular groove 64 for retaining a split,
flexible stop ring 66. In its relaxed state this stop ring has a
diameter slightly smaller than the bore 60, and it provides a
temporary stop and positioning means for the distal end 34 of the
fiber bundle 26. This stop ring is preferably made of resilient
metal which is preferably gold or copper plate to provide a heat
sink and thus a means for shielding or blocking a peripheral
portion of the laser beam emitted from the distal end of the fiber
bundle. In essence, it enables the surgeon to place the laser
emitting distal end 34 of the fiber bundle against the stop ring at
precisely the desired stand-off distance from the epicardium to
create the desired initial opening therein, as shown in FIG. 5.
Since the stop ring shields the outer periphery of fiber bundle,
only a laser beam of a smaller diameter can pass through the stop
ring to strike the epicardium membrane.
The method of operation for the device 16 using the concave distal
head member 24 is illustrated in FIGS. 4 to 9. As shown in FIG. 4,
the surgeon first manipulates the device 16 so that concave surface
25 of the distal head member 24 can be moved against the outer
surface of the epicardium. At this point, as shown in FIG. 5, the
vacuum pressure supplied through tube 36 to the device 16 is
furnished through the central opening 28 of the distal head member
and causes the epicardium to bulge into the concavity of its flange
portion 27. This stretches the epicardium membrane to some extent.
At almost the same instant, the surgeon moves the fiber bundle 26
forward until its distal end 34 is stopped momentarily by the stop
ring member 66 at the desired distance from the epicardium. Now, a
laser pulse is initiated from the distal end 34 of the fiber bundle
26 to make the preliminary opening 31 in the stretched epicardium
membrane. (FIG. 6) Since the expandable stop ring has a small
inside diameter it reduces the size of the laser beam that strikes
the epicardium. After this opening has been formed, the surgeon
again uses the device control 32 to advance the fiber bundle 26, as
shown in FIG. 7. As this is done, the distal end 34 of the fiber
bundle moves forwardly through the stop ring 66, causing it to
expand radially into its groove 64, and the distal end of the fiber
bundle then moves into the myocardium. Simultaneously, laser pulses
with a full beam diameter are emitted from the distal end of the
fiber bundle as it moves forward to form a channel 18 all of the
way through the myocardium and the endocardium, as shown in FIG. 7.
After the channel has been completed, the fiber bundle 26 is
retracted back inside the distal end member 24 and inwardly from
the ring member 66, as shown in FIG. 8, to be ready for forming the
next channel. As the channel is being formed and during retraction
of the fiber bundle, a vacuum through the distal head 24 is
maintained which helps to remove debris from the channel 18 and
also to draw blood into it to start the revascularization process.
After full retractions of the fiber bundle, using the device
control 32, the removal of the concave flange member 26 from the
epicardium, as shown in FIG. 9, allows the membrane to resume its
normal shape which tends to close the initial opening 31 formed
therein, thereby preventing excessive bleeding.
From the forgoing it is apparent that the present invention
provides an improved device for performing TMR procedures that
combines simplicity with efficiency to enable the formation of
effective channels for revascularization which will normally close
at the epicardium membrane to minimize post-operative bleeding
To those skilled in the art to which this invention relates, many
changes in construction and widely differing embodiments and
applications of the invention will make themselves known without
departing from the spirit and scope of the invention. The
disclosure and the description herein are purely illustrative and
are not intended to be in any sense limiting.
* * * * *